There has been conventionally disclosed a thin film transistor that includes a gate insulating layer containing a ferroelectric material (e.g. BLT (Bi4-XLaXTi3O12) or PZT (Pb(ZrX, Ti1-X)O3)) in order to enable rapid switching at a low drive voltage. Meanwhile, in order to increase carrier density, there has been also disclosed a thin film transistor that includes a channel layer containing an oxide conductive material (e.g. indium tin oxide (ITO), zinc oxide (ZnO), or LSCO (LaXSr1-XCuO4)) (Patent Document 1).
In a method of producing the thin film transistor mentioned above, a gate electrode of laminated films made of Ti and Pt is formed in accordance with the electron-beam evaporation technique. The gate insulating layer consisting of BLT or PZT is formed on the gate electrode in accordance with the sol-gel method. The channel layer consisting of ITO is further formed on the gate insulating layer in accordance with the RF-sputtering technique. Subsequently Ti and Pt are formed on the channel layer in accordance with the electron-beam evaporation technique, thereby forming a source electrode and a drain electrode. An element region is then isolated from a different element region in accordance with the RIE method and the wet etching technique (a mixed solution of HF and HCl) (Patent Document 1).